Day 6: the :has() pseudo-class

posted on 03.10.2022

It’s time to get me up to speed with modern CSS. There’s so much new in CSS that I know too little about. To change that I’ve started #100DaysOfMoreOrLessModernCSS. Why more or less modern CSS? Because some topics will be about cutting-edge features, while other stuff has been around for quite a while already, but I just have little to no experience with it.

:has() allows you to check whether a parent element contains specific children.

In the following example, each .form-item that contains/has a child with the aria-invalid attribute set to “true” displays text in red color. (currently only in Chrome/Edge 105+ and Safari 15.4+)

<form>
  <div class="form-item">
    <label for="name">Name</label><br>
    <input type="text" id="name" required aria-invalid="true">
  </div>

  <div class="form-item">
    <label for="email">E-Mail</label><br>
    <input type="text" id="email">
  </div>
</form>

.form-item {
  --color: #000;

  /* The default color is #000 */
  color: var(--color);
}

input {
  /* The default border-color is #000 */
  border: 1px solid var(--color);
}

/* If the .form-item contains an element with [aria-invalid="true"], 
the text and border color changes to #F00 */
.form-item:has([aria-invalid="true"]) {
  --color: #F00;
}

See on CodePen

Further reading

• Day 8: nesting :has()
• Day 16: the specificity of :has()
• Day 26: using combinators in :has()
• Day 50: :has(:not()) vs. :not(:has())

Do you want to learn even more awesome CSS?

I'm running a workshop with my friends at Smashing Magazine in which I introduce you to the most useful modern features in CSS and show how you can implement them today in your code base to improve scalability, maintainability, and productivity.

Learn more about the workshop!

Overview: 100 Days Of More Or Less Modern CSS